<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div{
            display: flex;
            width: 800px;
            height: 400px;
            background-color: pink;
            flex-wrap: wrap;
            /* 因为有了换行，所以侧轴上控制子元素对齐方式用item-content */
            /* align-content: flex-start; */
            /* align-content: center; */
            /* align-content: space-between; */
            align-content: space-around;
        }
        div span{
            width: 150px;
            height: 100px;
            background-color: purple;
            margin: 20px;
        }
    </style>
</head>
<body>
         <!-- align-content只用用于子项在出现 换行(多行) 情况下，单行下没有效果 -->
       
    <div>
        <span>1</span>
        <span>2</span>
        <span>3</span>
        <span>4</span>
        <span>5</span>
        <span>6</span>

    </div>
</body>
</html>